A pipeline is frequently in the form of an inner liquid carrying pipe disposed within a rigid outer casing. In some cases, plural liquid carrying pipes are disposed within a single rigid outer casing. The carrier pipe, or pipes, disposed within an outer casing is frequently provided for water and sewer mains within highway and railroad crossing pipe casings to maintain carrier pipe alignment, restrain the carrier pipe against flotation or other movement, or maintain the carrier pipe in a fixed position and orientation such as per grade requirements in the case of a gravity sewer. In the case of a single carrier pipe, a single spacer is frequently disposed about the carrier pipe and between the carrier pipe and the outer casing to maintain stationary positioning and fixed spacing of the carrier pipe relative to the outer casing.
Earlier approaches to maintaining positioning of an inner carrier pipe within an outer casing made use of wooden skids banded to the outer periphery of the carrier pipe with steel strapping. Not only is it difficult and time consuming to install the wooden skids, but the wooden skids also frequently catch on welded beads resulting in rotation of the carrier pipe and destabilizing of its joints. Moreover, the wooden skids and steel straps are susceptible to breakage, requiring removal and reinstallation.
The wooden skid approach to positioning a carrier pipe within an outer casing has generally been replaced with casing spacers comprised of stainless steel, galvanized steel, or epoxy coated steel. This type of casing spacer employs two or more shell members each including an inner portion disposed about and engaging the inner carrier pipe and an outer portion engaging the inner surface of the outer casing. The plural shell members are securely coupled together and attached about the inner carrier pipe by means of plural nut and bolt combinations, with each shell member's inner portion being arcuate in shape and its outer portion including plural spaced ribs attached to and extending outwardly from the inner portion and engaging the outer casing's inner surface. These spaced ribs are commonly called “risers”.
An example of this later type of casing spacer can be found in U.S. Pat. No. 6,571,832, issued on Jun. 3, 2003 and assigned to the assignee of the present application. The individual sections of this type of casing spacer are sized to fit a specific carrier pipe diameter. To accommodate an inner carrier pipe having a different diameter, at least one casing spacer segment must be replaced with another segment of a different size. In some cases, both casing spacer segments must be replaced when used with an inner carrier pipe of a different diameter. This approach requires a large casing spacer inventory to accommodate a wide range of carrier pipe sizes. In addition, while incorporating non-slip members for more securely engaging the inner carrier pipe, the location of these non-slip members on the casing spacer segments limits their frictional engagement with the carrier pipe reducing the likelihood for fixed attachment to the carrier pipe. In addition, these non-slip members are subject to impact damage because of their position on the inner portion of the casing spacer.
The present invention addresses the aforementioned considerations of the prior art by providing a flexible casing spacer comprised of two complementary segments which are adapted for tight-fitting engagement with inner carrier pipes having a wide range of diameters for securely maintaining the carrier pipe in fixed position within an outer casing. The inventive casing spacer eliminates the requirement for a large inventory of casing spacers of different sizes to accommodate inner carrier pipes of various diameters.